Gasoline prices climb toward $4, diesel already past that mark

The U.S. Department of Energy, in its weekly report May 12, listed the average nationwide retail price for a gallon of regular gasoline at $3.72.2 a gallon. The average price for a gallon of diesel fuel was $4.33.1. The West Coast — California, in particular — led the nation in both fuel categories.

California has its own gasoline reformulation program, which is more stringent than the federal requirements.